(CNN) - Sen. Mark Kirk of Illinois, who suffered a severe stroke to the right side of his brain in January, said Friday that he has transitioned into a new phase of the recovery process.

"As I move into a new phase of outpatient rehabilitation for occupational and physical therapy, I will continue to work hard in order to further regain my strength," Kirk said in a statement.- Follow the Ticker on Twitter: @PoliticalTicker

Kirk, 52, thanked his doctors and physical therapists at the Rehabilitation Institute of Chicago, where he has participated in intensive walking studies.

"With their encouragement and help, within the research trial I walked an average of 3,677 steps per day, a total of 14.79 miles over ground and on the treadmill, and up 145 flights of stairs," he said.

He entered the program in May after being released from the hospital and posted a web video showing his journey in learning to walk again.

Elected to the Senate in 2010, Kirk previously served as a U.S. House member for 10 years. He's best known for eventually winning President Barack Obama's Senate seat after Obama was elected president in 2008.

Kirk bested Democrat Alexi Giannoulias, the state treasurer who had strong support from Obama. The seat had been vacated by Democrat Roland Burris after he was embroiled in scandal surrounding his appointment by then-Illinois Gov. Rod Blagojevich to fill Obama's seat.